1. Field of the Invention
The present invention relates to the field of low bulk seams for use with papermakers machine fabrics, and more particularly relates to such a seam for use in monofilament fabrics.
2. Prior Art
The prior art has for some time, recognized that papermakers fabrics may be flat woven and then seamed in order to produce an endless fabric on the papermaking machinery. The earliest attempts to form seamed fabrics utilized a technique of back weaving the flat woven fabric ends to produce essentially an endless belt. This technique was both time consuming and difficult. It was later recognized that flat woven fabrics could be made into an endless belt by use of hooks or loops which were affixed to the respective ends of the flat woven fabrics and then made to interleaf with each other so as to form a channel wherein a pintle hook or joining wire could be inserted. Other recent attempts to join flat woven fabrics to an endless belt have utilized a coil which was affixed to the respective ends of the flat woven fabric and interleafed to form a channel for receiving a pintle or joining wire. In recent years, some monofil fabrics have been seamed by a technique of selecting alternate warp ends which are formed into a loop and then back woven into the fabric so as to retain the end in the fabric. Once again, the loops so formed were interleased to form a channel for receiving a pintle wire or joining wire.
As noted, one prior art attempt at making pin seams in papermakers felt has been to utilize alternating warp ends which are formed into a loop at the ends of the fabrics that are woven back to the body of the fabric. The loops formed on either end of the fabric at the ends thereof are made complementary and mate with each other so that a long wire or pintle may be inserted through the channel formed by the loops to join the two ends of the fabric into an endless fabric belt. The seam thus formed is not substantially thicker than the normal thickness. However, the process of weaving the warp ends back into the fabric in order to form the loops and the associated fabric weakness have lead to reduced wear characteristics for pin seams formed by this back weaving method.
Also as noted, a second prior art attempt used various coil type seams wherein coils or spirals are inserted along a fold line and the fabric is folded back over itself or otherwise attached to itself so that the coil may matably receive a coil similarly attached to the other end of the fabric. A wire or pintle is then used to join the seam as mentioned previously. While coil seams have achieved some success, the additional thickness and thickness irregularity attended with such seams has limited their applicability, their life, and/or the reliability thereof.
To date, the prior art attempts to produce a pin type seam in a monofilament fabric have resulted in a high fabric bulk adjacent to the pin seam area and undesirable running characteristics for the belt as a result of the seam. It has long been recognized that the seam area of the flat woven fabric which has been joined to make an endless belt is a major contributor to product defects and fabric failure.